The ever increasing demand for high spectral efficiency spawned by a variety of next generation wireless services places considerable strains on modern satellite communication systems. Conventionally, signaling techniques relied on a set of transmission and reception filters that satisfied the Nyquist signaling criterion for ensuring inter-symbol interference (ISI) free reception. These conventional systems use root-raised cosine (RRC) filters that satisfy Nyquist's ISI free reception criteria. However, to achieve ISI free reception, Nyquist's criterion imposes constraints on the maximum symbol rate and signal power spectrum density.
As a consequence, there is an increasing interest in transmission techniques that introduce a certain amount of controlled ISI at the receiver. Examples of such techniques include Continuous Phase Modulation (CPM), Faster-than Nyquist (FTN) signaling and partial response signaling. All of these techniques seek to improve spectral efficiency by introducing a certain amount of controlled ISI at the receiver.